lol

local str = 'absclkdallskd'
local d, e = {}, {}

local function transform(s, st, border, s_len, b_len, c)
  local stream, result, i = '', '', 1
  while i <= #s do
    local a, b = ''
    if st then -- if decoding
      b = string.byte(e[s:sub(i,i)])
    else -- if encoding
      b = s:sub(i,i):byte()
    end
    for o = 0, border do
      a = bit32.extract(b, o)..a
    end
    stream = stream..a
    if #stream == s_len then
      for j = 1, #stream, b_len do
        result = result..string.char(tonumber(stream:sub(j, j+c),2))
      end
      stream = ''
    end
    s, i = s:sub(2), i-1
  end
  return result
end

local function encode()
  for i = 1, #str do
    local o = str:sub(i,i)
    if not d[o] then
      d[o] = true
    end
  end
  for i in pairs(d) do
    table.insert(e, i)
  end
  d = nil
  table.sort(e,function(a,b)if a:byte()<b:byte()then return true else return false end end)

  if #e > 128 then
    return nil
  elseif #e <= 128 and #e >= 65 then -- 7
    if string.byte(e[#e]) <= 127 then -- standart
      print(#e, '7s')
    else -- adaptive
      print(#e, '7a')
    end
  elseif #e <= 64 and #e >= 33 then -- 6
    print(#e, '6a')
  elseif #e <= 32 and #e >= 17 then -- 5
    print(#e, '5a')
  elseif #e <= 16 then -- 4
    print(#e, '4a')
  end
end